The present invention relates to a method of manufacture and a device for the manufacture of a display device in which individual display device substrate-units are separated from stacked mother substrates.
A planar panel type display device is constituted such that two sheets of large-sized substrates (referred to as stacked mother substrates hereinafter), formed of a first substrate (in general, a glass substrate, simply referred to as a substrate) and a second substrate which are laminated to each other while incorporating pixel regions of a plurality of unit display devices, are separated into individual display device substrate-units, and drive circuits are incorporated into terminals pulled out from the pixel regions. To separate the workpiece into individual display device substrate-units, for example, as described in JP-A-6-48755 (literature 1), scribe lines are formed on the first substrate, and, after turning the stacked mother substrates up side down, the stacked mother substrates are broken along the scribe lines. Next, scribe lines are formed on the second substrate and the stacked mother substrates are again turned up side down and are broken along the scribe lines. Thereafter, peripheral portions for exposing terminal portions are removed as wastage.
In this breaking operation, a so-called scribing and breaking method is adopted. In this method, the stacked mother substrates PN on which the scribe lines are formed are mounted on a break table which has a metal plate, such as a stainless-steel plate, mounted on a cushion sheet made of rubber, sponge or the like in a state such that the scribe lines along which the substrates are to be broken are set at the break table side, and, thereafter, the stacked mother substrates are broken by being hit by a breaking bar made of a rubber member or the like from a side opposite to the scribe lines along the scribe lines or by having a pushing force applied thereto.
Further, JP-A-6-3633 (literature 2) discloses a scribing and breaking method in which respective stacked glass substrates are clamped using a pair of clamps while sandwiching the scribe line and the stacked glass substrates are broken by rotating one clamp at the scribe line.
FIG. 19 is a diagram showing a working example of the use of scribing lines in a conventional scribing and breaking method. Here, an example in which 9 display device substrate-units are obtained from the stacked mother substrates formed of two substrates SUB1 and SUB2 is shown. On a surface of the first substrate SUB1 (front surface of stacked mother substrates in FIG. 22), eight scribe lines SBL1 in total consisting of four scribe lines in the X direction and four scribe lines in the Y direction are formed. With respect to the scribe lines SBL2 which are formed on the surface of the second substrate SUB2 (back surface of the stacked mother substrates), in addition to eight scribe lines SBL2 which are formed at the same positions as the scribe lines SBL1 formed on the first substrate SUB1, four additional scribe lines SBL2 are formed. Accordingly, twenty scribe lines in total become necessary at front and back surfaces of the stacked mother substrates.
That is, in the periphery of the stacked mother substrates, the scribe lines are formed at the same positions on the front and back surfaces of the first and second substrates and portions which are separated along the scribe lines become the wastage. Further, with respect to the scribe lines which are formed inside the stacked mother substrates, there exist scribe lines which are formed at the same positions at the front and back surfaces and scribe lines SBL2 which are formed at different positions from the scribe lines SBL1 only with respect to the second substrate SUB2. The substrate between the scribe line formed only in the second substrate SUB2 and the scribe line which agrees with the scribe line formed on the first substrate is removed as a wastage to expose terminal portions of the individual display device substrate-units.
FIGS. 20A to 20C are diagrams which show sequential steps in separating the stacked mother substrates on which the scribe lines are formed into display device substrate-units by breaking. FIG. 20A shows a state in which the stacked mother substrates PN, which have already been broken along the scribe lines SBL1 at the first substrate SUB1 side, are broken along the scribe lines SBL2 at the second substrate SUB2 side. The stacked mother substrates in which the first substrate SUB1 has been broken are placed on a break table BKT using a transfer device TFD. At this point of time, the scribe line SBL2 of the second substrate SUB2 to be broken is placed on the break table BKT side.
Next, as seen in FIG. 20B, the stacked mother substrates PN are hit from right above the scribe line SBL2 at the second substrate SUB2 side in an arrow direction P using a breaking bar, thus applying the pressure to cause breaking at a break end BK2.
As a result, the stacked mother substrates PN are separated into display device substrate-units PNL at the break end BK1 of the first substrate SUB1 and at the break end BK2 of the second substrate SUB2, as seen in FIG. 20C. Symbols WT1 and WT2 indicate undesired peripheral wastage and WTM indicates an internal wastage (also referred to as core-removed wastage) which constitutes an undesired wastage of a terminal exposed portion of each display device substrate-unit PNL.